Key:flood prone
| flood_prone |
| Description |
|---|
| Whether or not the feature is likely to flood after very heavy rain. |
| Group: Hazards |
| Used on these elements |
| Useful combination |
|
| See also |
| Status: in use |
| Tools for this tag |
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An area or way, that is prone to flooding. This is mostly applicable to roads that go under water after heavy rains. Flooded roadways are often very dangerous to cross and many people die each year as a result.
The default value is flood_prone=no and should not be used
A floodplain is an area around a waterway where it could break its banks and flood the surrounding area. A floodway is a crossing along a waterway or floodplain.
Mapping waterway crossings
To map a simple floodway crossing that does not have a bridge-like structure. Apply a tunnel=culvert tag to the waterway, and put flood_prone=yes on the intersecting highway.
Mapping flood prone bridges
For a flood prone bridge, you should ensure a bridge=* tag is on the relevant highway and add flood_prone=yes. Nothing really needs to be done to the waterway since the bridge is a structure above the waterway.
Mapping flood prone highways
If the area is surrounded by flood plains or is otherwise at risk of flooding. You should apply a flood_prone=yes to the exact part of the way that is likely to go underwater. However, if you don't this information precisely, you can also tag flood_prone=yes on a single node.
General situation
Photos were taken south of Barellan, in the Mirrool Creek floodplain.
The above photos are of the Gwydir highway east of Moree
Rendering and possible usages
Flood prone areas don't have water across them 99.9% of the time, so there isn't any perceived benefit in rendering these areas most of the time.
However, the information can help routing software to avoid potentially hazardous crossings after heavy rain.
Furthermore, some Emergency services may find it useful to have their own flood mapping that highlights these and similar tags.
Similar tag ideas
- It might be useful to tag the markers that indicate depth of water when flooded, although similar markers can be found along river banks and tidal water areas
- It might be useful to tag how often flooding gets or covers a certain area, eg once in 100 years.
See also
- ford=* unlike flood prone areas, fords may be safe to cross if there is water across the roadway.
- Proposed features/floodplain
- "Landsat TM image analysis for identifying areas prone to flooding". In Spanish. Last updated 18 July 2011; accessed 31 July 2011.
- OpenHazardMap – risk mapping project, including flooding